To wireless



Jul 10,1928. 1,676,744

G. W. PICKARD ELECTRICAL AMPLIFIER Filed Feb. 1923 6 Sheets-Sheet 1 IN V EN TOR S G Greenleqflllffl'erfickard BY T ATTORNEY d r M 3 mm 7 t r e 6 mm 1 m .i w m h S 6 M H w R Y own 3 mu m mam Hmw PS .nI F m WNW awn L E l W P July 10; 1928.

ATTORNEY July 10, 1928.

G. w. PICKARD ELECTRICAL AMPLIFIER 6 Sheets-Sheet 4 Fil ed Feb. 5, 1923 ATTORNEY July 10, 1928. 1,676,744

G. w. PlCKARD ELECTRICAL AMPLIFIER Filed Feb. 5, 1923 6 Sheets-Sheet 5 PKFL 1 F FO IN V EN TOR B6 A TTORNE Y July 10, 1928.

1,676,744 G. W. PICKARD ELECTRICAL AMPLIFIER Filed Feb. 5, 1923 '6 Sheets-Sheet 6 aeen/eq/M INVENTOR zlzrerfickazd A TTORNE Y Patented July 10, 1928.

UNITED STATES GREENLEAF \VHITTIEP. PICKARD, or NEWTON CENTER, MASSACHUSETTS. ASSIGhTOR TO WIRELESS SPECIALTY APPARATUS COMPANY, OF B OSTON, MASSACHUSETTS, A

CORPORATION or New YORK.

ELEc iRIcAi AMPLIFIER. i

Application filed February 5. 1923;" Serial No 616,923

This invent-ion relates to improvements in electrical amplifiers of the thermionic type; and more particularly relates -to' -improvemcnts in the construction of"the"-co-- operating parts of such amplifiers of exist ing forms wherebythe user may construct his own amplifying set to be adaptedfor use at various wave lengths and orders of Wave lengths. A I he ohject of the invention is as just' stated and with particularreference to the tubesockct bases and the tube-couplers ort-ransformers in orderthat the userhiin'self may adapt his receiving and amplifying-set to use with various wave lengths of a given order (as for receiving radio broadcasting reception) and may alternate transformers or couplers of a given wave length range with others of a different wave length range, allwith afacility equal to'that heretofore enjoyed in respect of the removal and re placement of the tubes themselves;

The invention comprises the various constructions and arrangements disclosed herein, all with the view of providing an ampli' tier set as a whole wherein the various parts are adapted for both mechanical and electrical co-operation with one another 41ndwherein the tube-couplers or transformers-as well as the tubes themselves are capable of ready replacement and wherein the trans formers may be adjusted for degree of wave length variation within a given hand of Wave lengths.

Heretofore. the unskilled user or amateur has been confronted with equally unsatisfactory alternatives. Either, by the use of a complete set imlnufzu-tured in permanent form for use with a given limited range of wave lengths. he could operate within that wave length hand more or less advantage-- ously by the ordinary radio circuit tuning adj nstment-s; or. at the cost of very considerable trouble even after considerable experience. he could. after pur hasing the various like parts. himself assemble them in more or les fixed wave length conditions. The invention hereof makes it. possible to furnish separate parts' to such persons at very little expense. ho then by little trouble can assemble them under conditions as readily replaccable as heretofore in respect of the tubes them elves. and also under conditions of adjustability of the wave length of the transformers (couplers). if desired, so'that the wavelength conditions of the transformers may be precisely adapted to the wave length to which the radio circuits otherwise may-be adjusted/- Thereby the user not only may adjust his set'as' to any desired wave length, in respect of both" the transformer couplers and'the-radio circuits otherwise, butby replacement of the transformers-With 'transformers adap td for wave lengths of a very different order, such replacementbeing very readily accomplished, he may adapt-hisset for 'use With bands of wavelengths ofvery different orders; transmitted from various different stations. f I There will be described firsbthe transformers or couplers hereof,-then the constr'uctions of sockets adapted for use with eitherv the tubes themselves or with such couplers (the couplersbeing adapted to said sockets)"; andfinally-the set asa-whole will be '-'described ."comprising such cou plers, sockets and 'tubes,'the circuits of the" set and the entire set itself being'very greatly simplified in a'1ncchanical'sense; so that on the basis of asimple plan of circuit, a tyro without-previous experience may obtain the most nearl perfectly operating set possible, foi"tl ie inventions hereof permit the reduction to'an apparently simple form of the circuit arrangements heretofore used, which have been apparently as well as actually of a-complicated'nature.

.Of the drawings, Figs. 1-7 show transformers'or couplers adapted for use with the sockets of the invention; Figs. 8-10 and 16- 17 show the sockets constructed to be adapted for use with such couplers or transformers; Fig. 11 shows the'present' standard thermionic tube to which said sockets are adapted and to which the couplers are assimilated; Fig. 12 is a diagram of the circuits of=one of the various forms of am plifier hookups, showing in general the arrangement heretofore employed wherein the transformers or tube-couplers have been of fixed values or in permanently fixed locations; Fig. 15 is a diagram showing the same circuits of Fig. 12 but illustrating the relative simplicity of arrangement permitted by the inventions hereof. this diagram showing the successively alternating tubes and couplers as being offset or staggered with respect, to one another; Figs. 13 and 14 showing in perspective and bottom plan the completed structures assembled together and with-the circuits of Figs. 12 and 15.

In perspective in Fig. 13, the input portion of the receiving set' is shown at the left,

and"con'tains" the permanent-1y fixed devices of that part of the amplifier set as distinguished from the replaceablewtubes anri couplers shown at the right iiithefour sockets of the iIIVGHtiOXL .-In Fig.-=l4 the permanent parts of the set (other than the sockets) are shown'atlt-he left as in Fig. 13, but alLthe socketsshown in bottom plan at the right have been-rotated 180 as a whole about a longitudinal axis for. the purpose of showingthe-rcomplete extent of Ethecircuit lQHdS-z'fllld their connections in -the grooves in thebottoms of-the sockets, in a clear manner, and-m general correspondence with-thediagrani of Fig. 15.

, The-couplers.'T and T of Fig-.13 may like that; of either Figs 3, 0r-.7.-;-

The special transformers will be-described first, thenthe sockets, and finally the details ofconstruetion ofeach of them whereby they are combined as shown in the assembly of Figs.l3.a'nd.14;

Fig. .l-isa circuit diagram of one form of the/coupler, which zis a. -transformer. -Primary P, P and secondary S, S. with a permissive iron. core 0, are'interposed between i tubes U fand UH Primary-P, P is provided with. taps a,:b,-c, d,.and sccondaryiS, S with similartaps'm, 11., o, 71, connected to'parts of thewinding as shown: Over terminals of theseitapsoperatetwo-switches S, S which are mechanically connected'(Fig..=3) so that they move. together. The, connections of the taps-with the transforinerareso chosen that the'transformer-may be usedmsdesired over quitoa v:wide band of wave lengths withoutmaterialwchtlnaein efiiciency. At the point where the efiiciency falls off considerably and where it therefore may be desirableto ieplacem .givenitransfoi-mer with one wound for efficient use :with another order of wave lengths, such replacementimay be effectcd' by arrangements to be described later. The exterior connections of this transformer to the circuitleads to the tubes UKU are shown diagrammatically in Fig. 1. The upper end P-otthe primary is connectedto and-wave-length '(ahscisszc). \Vhcn switches S, S of Fig. l are respectively on switch points a and m, the performance of the transformer for the switches on the other tap points may be made to correspond with the successive Fig.2 curves A'B'C, A'-'B*C-' and .-\"BC, by properly choosing the connections to the windings of the leads from taps 1) b, c, (I and 1t, 0, 2. As the wave length of the received signals may vary, switches S, S are to be moved to corresponding taps and therefore the transformer will operate over a wide range of wave lengths, with satisfactory etficiency, as indicated by the full-line curve ABB, B BCK That is, the amplification is practically uniform and high between the wavelength limits corresponding to B and B.

In Fig. 3 is shown in commercial form a variable radio-frequency amplifiertrans former such as that shown diagrammatically in, Fig. 1. and operating at. different degrees ofvariation of wave lengths within-a wave length-band as is diagrammedin Fig. 2. .In Fig. 3 T is a metal casing enclosing the primary and secondary windings of Fig.1

suitably insulated and disposed therein, the switches S, S" of Fig. 1 being mounted on the topiof casing T andiconibmed to be operated simultaneously by a common central member in which they are mounted, the ends of these .swifches operating over contacts abcd and mum). On one.side.ofthe casing is a pin N, the purpose of which isto be described, as also the four contact prongs ext-endim from the bottom ofthe .casmg and connected respectively to the terminals of the two transformer windings. This Fig. 3 construction constitutes a self-contained unit. of about the: size of the ordinary thermionic tube'(Fig., 11)..

.-.The transformer of Fig. 3 is preferably employed for wave lengths not exceeding one thousand meters, although such construction may be used for longer waves. But above that length it is possible to use a tubecoupler of the type known as a resistancecoupler. The elements of such a coupler are shown in Fig. 4 as being disposed properly with reference to one another and connected to the four terminals indicated. In Fig. 4 R1 is a non-inductive resistance such as a carbon rod. C is a fixed condenser of suitable capacity, as of the order of .0005 microfarad. GL is a grid leak which may consist of a. strip of cardboard dipped in India ink.

or the like. These elements herein are placed and mounted inside a casing T, Fig. 5, similar to casing T of Fig. 3, and like that cars ing provided with a pin N and with four contact prongs projecting out of the casing below its bottom. corresponding with the bottom contacts of Fig. 4 and connected to the devices RI. C and GL of Fig. 4 within thecasing T, Fig. 5.

lUU

For some purposes. it is useful to have an amplifying transformer with a continuously variably adjustment instead of the step-by-step adjustment of the constructions of Figs. l3. Such a continuously variable transforn'ier is shown in section in Fig. (i and in elevation in Fig. 7. Insulating-material casing T has a slot Q, cut helically on its inside wall. In this slot Q. engage projecting portions .1, .l of a metal cap I. \Vhen cap I is rotated, it will move up and down in casing T. A rod L is screwed into the lower face of the top of cap I. Rod L at its lower end carries a laminated iron core IC. Surrounding 1C is a-slotted Winding form D. In the slots of form D are primary and secondary windings V of a radio-frequency amplifying transformer (similar to that of Fig. 1). These windings are connected by the leads shown to the four contact prongs projecting from the bottom of casing T. On the outside of cap I is marked conveniently a wave-length scale SC (Fi 7) corresponding to the optimum wave length at each position of core IC 6). When IC is nearly at the bottom of form D of transformer windin \V. the permeability ofthe space inside t e windings is at a minimum. So also is the wave length. \Vhen core IC is raised (by rotation of cap C by the knurl KN, Fig. 7) until it fills the space inside winding \V (in the position shown in Fig.6) ,the permeability and hence the optimum wavelength is at a maximum. Casing T also is provided with the pin L which, as in Figs. 3 and 5, is disposed at a certain point having reference to thefour bottom cont-act prongs, as will be described.

In Fig. 15 'is shown a portion of a multitube amplifier train embodying the invention, the showing being diagrammatic and illustrating the systematic compactness and ease. of setting up which are attained by the invention. This is to be contrasted with the arrangement of circuits employed heretofore as shown in Fig. 12, where the circuits themselves are the same as in Fig. 15. In Figs. 12 and 15 are shown two tubes U, U of an amplifier set or radio receiver. the input being assumed to be at the left. and the conductors at the right leading to further tubes and couplers or to rece ving apparatus such as telephones. Between the two tubes U. U is shown a coupler T which may be of any of the types hereof as shown in Figs. 3. 5 or 7. The same is true of the coupler T shown at the right.

The increased mechanical simplicity of the system diagrammed in Fig. .15 made possible. in connection with the abort construction of couplers by the use of the novel features of the sockets for both tubcs'and couplers, which features are shown in Figs. 810 and 16-17. The assembly of thcsc sockets with the circuits, and with the couplers and tubes, is shown in Figs. 13 and 14. In Fig. 13 is shown the assembly of the tubes of Fig. 11 with the sockets, couplers and-circuits; and Fig. 14 is a bottom view of the four sockets of Fig. 13, turned bodily end for end .180 about a left-toright axis, the circuits at the left of Fig. 14 remaining as at the left in Fig. 13. Fig. 14 illustrates the staggering of the sockets indicated in Fig. 15, and the connections of the leads to the terminals in the sockets to constitute the same circuit arrangement electrically as in Figs. 12 and 15.

In Fig. 8 is shown the general form of socket of Figs. 13 and 14. V

From end to end of a tube amplifier set, there are four continuous buses, and also, successively, the leads froma tube plate to a tube coupler, and from-a :tube-icoupler to-a-tubegrid. In Fig. 12 said successive leads are shown as inv a-sin 1e discontinuous line,-lettered"GD, P1), D, 'PD, GD. In Fig. lb-are shown-theafburbrises F, F", GB and PB a150, out-of'alinement with one another, said alternating leads GD, PD, etc., etc. Thus in F ig; 15 there-are six separate rows of leads. Thesesixdeads are taken care of by this idventionfiby we 1 of the socket devices, .eacli ob-Which has four grooves '(1-4, Fig. '8) in its*?base,one groove fort-a lead for-bus. This s'ocket'device consists .(Fig. 8).0f: two--parts, the socket base' BS and the'socket sleeve H. The four grooves 14*are:shown' as arches formed in the'bottomof base BS; Base BS may be molded of porcelain or'other suitable material as heretofore. Metal'shell or sleeve H is formed as heretofore with the bayonet joint Y- adapted to receive jointpin 'N (Fig. 11), of the standard tube, and adapted also to the standardized-coupler hereof also provided with pin N (Figs. 1-3, 4-5 and 6-7). Base BS may be molded to be maintained by the molding in a unitary structure with shell =H by means of some such construction of the lower end of shell H as that shown in "Fig; 16 to be described. The circuit leads (Fig. 8) pass through the grooves 14. In Figs. 13-14, foursocket devices like that of Fig. 8 are arranged in a row, with all the grooves in the same general direction, but the bases staggered so as properly to receive the six lines of circuit leads. All four bases BSBS may be secured to a common insulating base (not shown) as usual, by screws passing through the four holes 21 (Fig. 17) in the insulating base BS of each socket device.

In Figs. 9 and 10 are shown additional details of the socket device. The four grooves 1-4 in the bottom are shown in dotted lines in the top plan Fig. 9. The four contact springs 5-8 have their inner ends disposed as usual substantially equidistant from the center of shell H, such that such spring-ends willbe engaged by the con tactprongs of the. tubes (Fig. 11) as heretofore, and of murse by the .contact prongs of the couplers of this invention, as in Figs. 3,5 and 1 (see the appropriate terminal. lettering at thebottomof Fig. 10, corresponding.with-the:coupler-prong lettering of Figs. 3. and 7 .and 'the-itlibe-prong lettering 0t Fig.=11).: .'lhe.outer.zends of the four flat springs-M are disposed irregularly with re spect-to-the center-of shell H. beinglocated r ivelyzover the four groo\-'csL-4, at which points: the endspf the springs-are. secured-.3 under -the-heads of binding screws 9-12 on the uppeirendsi of the tei ininal bolts lettcrodiat theextreme bottom-of Fig. 10. Said bolts extend up-stlirouglr metal :connectOrSul'Z-Qt) mounted orzmolded inba'se BS. Said iconnectors J.7'=20 may be molded 'tot-he baseas'ishownin 16. In -Figs 9."1(1; theseaeonneetiorsi-cxtend :-l1p1above the top ofibaseBS-so that springs '5-8 resting on tl'tem'ilrewheld above the base sothat they can yield. to the loo'nt-a'ot prongs bf tube or uThQ alternative ltteu-designa tionof the terminal:bolts'Jat-the-bottomof: Fig. ind-iea te the a faetgthet any basecoi nectod socket-device' lilte .that'iof Figs. S''1O is ada ted for use-with either a' tube or a coupler, notwithstanding.tthatetliewireuits= of the tube and coupler are different from one another; fliis'being thefresultof the lead-arrangement of Figsdiiafirandathe staggcmdrelation of the tubes and couplerszwith their respective bases; --:'Ihe upper onfirst-of the alternative letteringEofithe terminalbolts of Fig. 10 is thatpertaining to :thew iring Fig. =14) -for either of -the second andthe tourt-lrsockcts from the left (BSand BS). i. c ter the couplers T% and T=-(Fig.-13). That is. those four wires or leads of the total of six lines of leads-uvhich extend to the four grooves of sockets BSand BS in the positions of the latter shownxin Fig. 14. are to be connectcd under the heads of the terminals of Fig. 10in the respective grooves 1-4. Similarly, as to the same construction of socket duplicated (Fig. 14) at PS and BS (first and third from the left, for the tubes U and U these sockets being set oil by two grooves from or staggered with respect to the other alternating pair of sockets BS and BS. so that the four straight lines of leads which extend to the grooves 1-4 of the sockets. properly are to be connected under the. heads of 'the terminals of Fig. 10 in said grooves. Pin N on the tubes and couplers (Figs. 3. 5. 7 and 11) when-engaged in bayonet joint Y of thebase-connected sockets (Figs. 8, 9 and 16), will guide the prongs of tube or coupler to the contact springs (Figs. 9 and 17) which are connected to the leads (Figs. 13 and 14) appropriate for the respective contact prongs. Take, for example. Figs. 11. 9. l0 and 14 O1 15, i. c., the case of a tube (Fig. 11), but similar (Io-the case of a -couplcr.- Pin (Fig. 11) i on the same side of the tube-base as pron s lIJPR and GS on its left and right. respe dierely. Joint Y of Fig.9 ison the same side of socket shell -1 as grooved in base 135, and sprm s 7, 8 (connected to tcrminals-PLPR and (IS, in Fig. 10) are on"the -left-.and right rcspectively of'saidtjoint-rY. 1mins when pin N-is caused to cnga e in jointtl'; the tube-prongs PLPR and S;\v.i]l' k electrical connection with the likerlettered hase-tern'iinals .of F ig..-, 10. Also ,pro'ngs FJ PO aAid-F POQtFig. 11 willamake elee! t-ricalcontact with like-lettered terminals-of Fi 10. Assuming lilliit'rtlle base.-sooket.in question is BS-(at the right, Fig..,14)-, sueh tube will beproperlyconnected in; the system, i. c... with its gl-ld;G=(-FigS.-1, 12i14 fl11d .15); connectedria terminal GS t'o-inputdead GD; its. plate PL connected to leacl- PD zvig itch mi'nal PLPR, and thelegzzs-ot itzs lfilamentaF. connected via terminals-EH10 18 ldz'F ;B ,O leads FF :-respecti\'ely.: To ill istratel the caseof a coupler, consider Figs. ;3,. 9,';1.Q and 14, being the case o't-a.transformenequp slt but similar to the case ofla tnbe,;(-Fig. 11'3), Pin N(Fig. 3) is locatedon apartjoflgasing T-arhich is on the side nearerfto prongsSPQ and P88, on its left. andjt'ightrespectively; so that when pin.Njsengageddnejoint 1, Fig. 9; nearest groove Land between; springs 'Z and 8 -on its left andrightrespectiyelym those prongs SP0 and PBB will make-ton,- tact with said springs 7 andfiS a'espeetiyely, tl iesc bci ng the springs. which are; connected to the terminals located above grooves 3 and 4 respectively-and lettered wrresp ondingly with prongs SP0 and PBB of Fig. 3. The remaining two prongs -ofI ig..3,. (SG and PRPL on the opposite side from'pin N) then naturally make electrical connection with the correspondingly lettered terminals SG and PRPL of Fig. 10 in grooves 2 and 1 respectively. Assuming that the. basesoclzct in question is BS Figlt next to right-hand socket), for the reception of transformer coupler T (Figs.-13'-and 15, second socket from left), such coupler (Tot Figs. 1 and 3) will be properly connectcdin the system. i. e., with the uppencnd of its primary (Fig. 1) connected (Figs. 1., 12. 14 and 1:3) via terminal PRPLto lead PD from plate PL of the first tube U, and the lower end of its primary (F ig. 1) connected (Figs. 1. 12. 14 and 15) via. terminal PBB to lead PB from plate battery BB; the upper part of the secondary of the transformer (Fig. 1) being connected via terminal 5G to lead G1) to the terminal GS of the grid of the second tube U and the lower part of the secondary of the transformer. (Fig. 1) being connected via terminal SP0 to lead GB to potentiometer P0.

The connections of the second tube U (like that of Fig. 11) to its socket- BS, and of the second transformer (like T of Fig. 3) to its socket BS (of Figs. 11 and 15) maybe traced similarly, in connection with the transformerconstruction of Fig. 3 and the circuit diagrams referred to above.

If transformerslike T of Figs. (L7 be used in Figs. 1315, they are placed in the sockets as just above described for transformers like Fig. 3 and for the standard tubes of Fig. .11. The same is the fact if resistance-couplers like that of Figs. 45 be desired to be used inlieu of the transformers ofFi s. 3 or 7.

v In ig.- 12 (showing the prior general arrangement of the circuits) there are only four true. buses, i. e., leads which extend from end'to end of the set,these four being the two filament buses .(F and F the third being bus PB'from transformer primary Bto plate .or-.B battery BB, the fourth bus being GB 'froni transformer secondaries S to potentiometer P0. There are two other kindsof leads, 'as stated, which successively alternate-from one end of the setto the other, i. e., the grid leads GD and the plate lead PD. InFi 12 both sets of leads G1) and PD .are .5 own in a discontinuous straight line. In Fig. 15 is shown in diagram the mannenin which the four-groove socket of ,this invention is adapted to this situation (Fig. 15 being a simplified showing ofFigS. 13-14); In Fig. 15 the two buses PB and GB (of plateand grid) are shown aslocated alongside one another at the top of the dia am; the two filament busesF, F? being .sfi own at the bottom; and the sets of leads PD and GD being located between said .two pairs of buses. Thus, turning to Fig-1? (where bases BS and BS are ofl'set from bases BS and BS- by the distance of two grooves), the two upper buses PB and GB .lie in grooves 4 and 3 of bases BS and BS. .Grooves3 and at of bases BS and BS are alined with grooves 1 and L). of bases BS and BS (due to the staggered relation ofbases), so that one of the short leads GD lies in, groove 40f base BS, one of four short leads PD, lies in oil'set groove 1 of base 138?, a Second of short leads GD lies in groove 4 of base BS and a second one of shoiztleads PD lies in groove 1 of base BS.;,said short leads .GD and PD being staggered alternately and successively by one grooves distance from one. another, and a roove3 or 4 .of each successive socket base Feingnnoccupied by any lead, there being in effect six lines of leads as indicated in Fig. 15. Thus, by the construction of sockets and-transformers hereof, the entire arrangement is I systematized and simplilied to,a very great degree as compared with the arrangements heretofore.

=From theabove, it is apparent that the invention provides a comparatively simple means for enabling the amateur to build his own set, and such a set which can ,be made readily, to do the duty of several separate sets (on different occasions and for widely different wave lengths bands) -merely,.by the substitution of transformers so wound as to be adapted for very difi'erent orders ,of wave lengths, the result being that the, user ,may

listen in on the various w ave. lengths other than the short ones now used inipo pular broadcasting, such as those of greater length which may infutnrebe in the broadcasting of entertainment, education, etc., of those of greater length for other communication. u I 1 I In F igs. 16-17 is shown anotherpractical form of socket device embodying the principles of that .of F igs, 8-10, F1g.. 16; is a Vertical section at 161 6 o i,Fig. l7 Fig. 17 being a bottom plan of ,the.. de vice,. the grooves in 1- 1 in insulat in base, BS c011 stituting little arched tunnels .above ..an in} sulating floor (not shown) of the complete amplifier set, to which'main floor or..:base the socket base BSis to be secured as by bolts through holes 21. Thebase BS is molded about the lower flared end of shell H (Fig. 16), so as to be combined permanentlytherewith. Likewise, the fourterminalsv 17-20 (two shown in Fig. .16), ,threadeclfor the binding screws, are. molded in baseBS which may be of porcelainor. other suitable insulating material. ,Contactspringsb-B i 16) may be set into and soldered to termma 1 i'20, as indicated. Thefour bindingfposts are lettered as in Fig. 10 to corres 0nd with the same partsof Fig. 14 in accor ance with the location of joint Y (Fig. 16) in shell H on the same side of the device with groove I 4. The contactv springs 5-8 (Fig. 16) are located below the lower wall of base .BS and with their inner-ends concenterin in the lower opening of shell H, although sleir outer-ends secured to'terminals 17-2O are located at different distances from the center in accordance with the location of said terminals in grooves 1-4 respectively; so that the four contact prongs of. either tube or tube-coupler (whicheverhappens-to be inserted in a given socket) will make electrical connection with the properlead when the sockets and leads are assembled as in Fig.

It is clear that in simplifying the system by this invention,- advantage has been taken of the fact that the transformer (and the resistance coupler of Figs. 4.5) has four terininals,-as in the case of the tube itself; and it is that fact which lies at the base of the invention. Also the grooves of the socket bases may take .any desired form such as perforations through the bases. The amplifier set may comprise one or more of each of a tube and a'couplen.

"FThe socket devices ('ifFigs. '13'-'15may beof' any of thegforms ofi-Figs; 840, 16 1 7' or any'other fortnfinvohling theprinciples thereof. The cout-act'springs 'for each of thesc socketdevices are" referably 'all ofthe samelength; as 21 Stan ard pait it being a sim le ina'tte'r to'locatethemetallic" connectors'at the particular point of the-icngth of each groove which will permit? of' such springs 'of uniform lengths." s 1 t 2 5' 51x 11!; L! *1. Ina thermionic tube'amplifier; thecom hination :the thermionic tube, a tube coupler' mlthe" amplifier clrciiit leads "ar ranged in siii rowsfeach of the tube and coupler having four egterior-bdntac tptertni rials,"of"du'pli't*ate sticlcetsTorh risi receptacles which, together w'ith h f-"t and' co upleig are constructed for the detachable reception dfs'ucli'tube andcouplenmnd' coinprising bases'lform edw ith -furigrom-e for the' reception ot tii lea'tist 'sai'df socketbe infg providedr "Contact ternunils "ar ran-ged to-operativlyjwith 'tlle arrangement of the 'four contact jtermin'als of the tube and coupler respectively for the-mi'rl-ual em gagehient of' said'contlx'ct terminals when the tube and can leiarelle'ld iithereceptacle; saarsoekew prd i'ddalswn' ith corilictors 'e'lcctricallljjconnect d with the contact EerniinaIS'ofthEsbckctQ and constructed flirfltichab'le bbhfiectibnfifiththe leads in thgrooves of the socket-j? 'nid sztidfduplieatei sockets beift g" airranged'in mumm stag ger'ed positibnsioi the coffiofint' reception of the *sitc ionfs of leads in? the'eightsocket= g ic =i 2i? In anemia c tubeamplifienthe coma hinatio'nfn'ith' the thernjllonic tube; a-"t ube coupler and the amplifier circuit leads} a'r ranged ir i's'ix fows-,- eachi"of"the"tube{and coupler having fou'r exterior contact "ter'rn'rna ls, of duplicate socketsc'oin'p'risi n g- 'recepr ta'cles u hichjtogether with the [tube and.

coupler 'are constructed Poi-"the detachable receptionof such tnbe'and coupler; said sockets comprising-bases fofin'ed with four grom es to. rceivithe circuit leads and-said sockets beingprovid'ed with contact rerm'r" nals ai'ra aged co operatively \yithj the arrangement of the fou'r" extenor contact terminals of the tube a-mi couplerrespect-itiely to permit mutual-contact of-the respective contact terminals \vhen the tube and con leiarc'lreld in the-receptacles: and said so ts being arranged in relatively staggered positions for m cron-joint, rece tibn of the six lows of leads in their cl; 1 grooves; the leads of the grooves-of each offfthesockcts being electrically connected with the contact terminals hf the mckcl's whereby when the tube and coupler-are held in-the reccptacles, they will beelectricallyconnected with the six circuit leads.

I}. In a thermionic tube zimpl'i-fierfthe combination with a thermionic'tube, of atrausformer-coupler comprising primary and secondary windings in mutually inductiverelation, and the amplifier circuit leads ar ranged in six rows, of a casing'enclosing the windings of the transformer; duplicate sockets comprising receptacles which" togetherwi'th the tube and easing of them-ansdrmer are constructed for the detachable" teminals electrically connected ivith the leads in the groovesgsfld transformer casing andtubes.- being provided with efittei-ior tact terminals arranged for cngageh m: with the contact'termi'nals' of'the sbc .ts'

when in the receptacle the reo.f;""liiidskiidi sockets beingi arrahgcd in relatively htlr'g' g'cred positions so that their-grooves mu "6 the; sixrowsofleadsl' I "f f 12f In 'athrmionic tube a|npii-fier;"the com' l iiti'onf with a thermionic -'tube"and a'co1rpling"transforu1er as self contained' im'its separate from' one. another-and" from {their sockets'jcircuil leads for' said tribe and transformer, and contact terminals-ou said tube and "transformer-miles )onding l-witk saidci'icuit lads'fof' niea'ns' a'lyustiiig the primaryand secondary Flvindings' ofsaid transformer to' va "its "efiec gtlvc em length; and substantta ll duplicate fior receiving the tube and trau sforijier firesgj ectively and'onn ctihgwhoni with said circuit leads of the amplifier; the construe:- tion and arrangement of the 'contact-jtcrmfi n'als' of said transformer being similar to thosc= of saiditubc, \Yhereby citlherYsockct' may beemployed witlf either the tulbcbrthe transformer; and whereby different tram formers having substantially the sa megcon struction and arrangement of mmtact terminals may be placed successivelyiii-circuit in agiven socket.

5. In a thermionic tube amplifier, theconibination" with electrical circuits andcontact: carrying amplifierelements including"? tube and a coupler, of a socket for-fsuchan element which comprises a-n'insulating base fbrmcd with si-lbsbantially" parallel grooves for the reception-of the'circuit leadsfand a -receptacle combinedwith 'said base and constructed for the detaclwible receptiois of such amplifierelement; and contact time; nals carried by the socket and arranged to be'engaged lay-the contact terminals-carried by the amplifier element when such elementisin place'in the receptacle; said socket QOIF tact terminals beingconstructed for detach able electrical connection with the ain pliifier leads in the grooves of said insulating-base of the socket. N

6. In a thermionic tube amplifierg the saidcombination with electrical circuits and contact-carrying amplifier elements such as a tube and a coupler, of a socket wlnch comprises an insulating base formed with grooves for the circuit leads, and a receptacle constructed for the detachable reception of such amplifier element; said socket carrying contact springs coneentering toward the receptacle and arranged to make contact with the contact terminals carried by such amplifier element when in the receptacle; and connectors mounted on said base adjacent the grooves therein and constructed for detachable electrical connection with the circuit leads in the grooves; the outer ends of said contact springs being mounted in electrical connection with said connectors adjacent said grooves.

.7. In a thermionic tube amplifier, the combination with electrical circuits and contact-carrying amplifier elements such as a tube and a coupler, of a socket which coinprises a receptacle constructed to detachably receive such amplifier element, and a base of moldable insulating material molded about the receptacle to constitute a unitary structure of base and receptacle, said receptacle being shaped to cooperate with tie moldability of the base to that end; and said base being formed with grooves for the reception of the circuit leads; connectors molded in said base adjacent to the grooves therein and constructed for detachable connection with the leads in the grooves; and contact springs arranged substantially radially in said socket, having their outer ends mounted in electrical connection with said connectors adjacent said lead-grooves in the socket; and said contact springs having their inner ends located to be engaged by the contacts carried by the amplifier element. when the latter is in place in the receptacle of the socket.

8. In a thermionic tube amplifier, the combination with a thermionic tube and a tube coupler as separate self-contained structural units, of substantially duplicate sockcts for said tube and coupler, said sockets being constructed for detachable connection respectively to the coupler circuits and tube circuits of the amplifier set; and said sockets being formed with grooves for the reception of their respective sets of circuit leads; the sockets being also constructed with contact springs extending from points over said grooves radially inward to central mutually neighboring points; and said coupler having contact terminals and an arrangement thereof which simulate those of the tube, said socket terminals being constructed in each case to make circuit contact with the centrally disposed portions of the contact springs of the sockets; and said coupler being provided with means for guiding it to position in its socket to assure engagement of its terminals with the appropriate contact springs of the socket.

9. In a thermionic tube amplifier system having a given number of buses for tube and tube coupler extending from end to end of the amplifier set, the combination with a plurality of sockets having a like number of grooves receiving said buses and having a like number of contact connectors between said buses and tube and coupler, the tubes and amplifiers corresponding in number to said sockets, each tube and coupler having a number of contact terminals which corresponds with the number of said buses, the number of grooves in each socket, and the number of. socket contact connectors.

10. In a thermionic tube amplifier, the combination with the tubes and coupling means therefor, and the four continuous buses and the tube plate leads and the tube grid-leads arranged in two lines of leads; of sockets for the respective tubes and coupling means each socket comprising a sleeve and a ha e, each base being formed with four grooves, and the bases and their grooves receiving the two lines of leads; said sleeves of the sockets receiving the respective tubes and coupling means.

GREENLEAF WHITTIER PICKARD. 

